Making the most of a shuttle derived booster for the CEV

[gunsandrockets]

http://www.astronautix.com/lvs/srbcev.htm<br /><br />http://www.spaceref.com/news/viewnews.html?id=1040<br /><br />http://www.safesimplesoon.com/nextstep.htm<br /><br />So much for background. It looks as if it's a done deal as far as choosing the SRB derived booster for the CEV launch vehicle. I'm doubtful the SRB is the best solution. Watching the video on ABC Nightline of a Shuttle crew getting bounced around the cockpit by the vibration of the solid rocket boosters during launch was enough for me.<br /><br /> But what are some possible upsides to the SRB? What unique qualities of the SRB could be exploited for maximum benefit? Yes, yes I'm sure we have all heard more than enough from ATK, Griffin and others who sing the praises of Shuttle derived hardware, but I'm thinking of SRB benefits which have not been mentioned so far.<br /><br />For example, of the semi-reusable space shuttle arguably the solid rocket boosters are the most successfully reusable part of the whole system. So right off the bat the new CEV booster will have a reusable first stage. Why not exploit that by making the CEV itself as reusable as possible? Maybe even the second stage can be designed for orbital reuse, perhaps by refuelling. That would make the CEV + booster the most reusable manned system yet.<br /><br />Plans for the SRB derived CEV booster anticipate using a LH2/LOX burning second stage. That choice would provide the most performance for the least weight. But there are other possibilities, what about using storable liquid propellants like on the Titan booster?<br /><br />One advantage of a solid propellant booster is it is always ready to launch, unlike rockets which use cryogenic propellants. If the second stage of the CEV booster used storable liquid propellants

 

[mattblack]

What bothers me is that whatever architecture and vehicle design is chosen, even if it was the best, you can bet your life that somebodies on this board will be unhappy about it. EELV-derived, Lifting Body or capsule, Shuttle-derived or CEV-on-a-stick, one way or another there will be whiners and gripers here venting their spleen.<br /><br />So what, you say? It's a free-speech board! True enough. I just mean that you can't please all the folks all the time. I wouldn't want blind obedience to Nasa and it's new VSE Architecture, but I would strongly advocate loyalty and support, because these next 4 years are going to be tough for space lovers and space geeks everywhere.<br /><br />Be it private travel to space or Mike Griffin and his magnificent (wo)+men and their flying machines, they're going to need all the support and backup from us that they can get.<br /><br />I want this era we're in now to be the one where our Granchildren say "That was when the tide turned and Space became a human priority and adventure". <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[gunsandrockets]

"Hypergolic propellants are very expensive "<br /><br />If propellant costs were a primary design consideration than NASA wouldn't use difficult to store liquid hydrogen or difficult to manufacture solid rocket fuel grain either.<br /><br />I think it's fair to also point out that hypergolics are the most reliable performing engines for starting and restarting in space. That's why hypergolics were used in the Apollo service module and lunar lander, that's why hypergolics are used for virtually all deep space unmanned landers and orbiters.

 

[rocketwatcher2001]

Solids are much easier (less costly) to work with/store than hypergolics. That's why all of the Titan ICBMs were replaced by Solid Fueled Minuteman or MX missiles. Titans, and their facilities were too much of a pain in the rear to maintain. <div class="Discussion_UserSignature"> </div>

 

[krrr]

Sizeable LOX/LH2 upper stages are extremely useful in terms of performance. Typically, payload capacity is increased by 40 or 50 percent if a storable propellant (or LOX/Kerosene) upper stage is replaced by a cryogenic one. ("Sizable" meaning something larger than the little stages used by Atlas V, Delta 4, Ariane 5 etc.)<br /><br />So for an SRB stick I guess LEO performance would drop to something like 13 tons if the projected LOX/LH2 stage would be swapped with a storable propellant one of the same mass. Enlarging mass might also overextend the SRB, its raw power notwithstanding.

 

[gunsandrockets]

"So for an SRB stick I guess LEO performance would drop to something like 13 tons if the projected LOX/LH2 stage would be swapped with a storable propellant one of the same mass."<br /><br />26,000 pounds? Hmm...<br /><br />Two points.<br /><br />First, I note that the current plan for the CEV is for four man deep space missions and for three man missions to the ISS. The Russian Kliper spacecraft is a six man design and has a mass of 13 tonnes complete with all LEO mission systems. I doubt the mass of the CEV will exceed the capability of a booster with an SRB first stage and storable propellant second stage.<br /><br />Second, I think your estimate of the storable propellant stage performance is too low. Low end estimates from ATK of the SRB with LH2/LOX second stage are 48,000 pounds to LEO (perhaps that is with a 4 segment SRB and J-2 engine second stage). High end estimates from ATK are for 65,000 pounds to LEO. ISP for storables are over 300, for LH2/LOX ISP is 420 for the J-2 engine, 450 ISP for the SSME, and 465 ISP for the RL-60.<br /><br />So taking these numbers into account the low end performance for a storable propellant second stage would be 36,000 pounds to LEO (16 tonnes). High end performance maybe 20 tonnes to LEO. That tracks since a standard SRB with storable propellant second stage would be very comparable in mass and propellant mix to the Titan IV rocket booster which can lift 17 tonnes to LEO.

 

[gunsandrockets]

"Solids are much easier (less costly) to work with/store than hypergolics. That's why all of the Titan ICBMs were replaced by Solid Fueled Minuteman or MX missiles. Titans, and their facilities were too much of a pain in the rear to maintain. "<br /><br />And solid propellant rockets have crappy ISP compared to almost any liquid propellant rocket. Which is why the Soviets had such a throw-weight advantage over the U.S. ICBM force during the cold war. And which is why rockets with all stages using solid propellant are almost exclusively military.

 

[gunsandrockets]

"You obviously fail to understand the difficulty in using hypergolic propellants. "<br /><br />Funny.<br /><br />There are costs and tradeoffs involved no matter what particular choices are made for a manned launch system. One choice that has been made is to use the shuttle solid rocket booster. I believe that is a poor choice, that the SRB drawbacks outweigh the benefits. But as long as the SRB is the choice I'm trying to see how the benefits of the SRB could be exploited instead of just p*ssed away for nothing.<br /><br />If I was going to design a manned launcher from scratch I wouldn't pick solid rockets or hypergolics. I would pick an RP-1/LOX burning first stage and an LH2/LOX burning second stage. The common core booster concept looks like a good idea too.<br /><br />I imagine something like two SpaceX Falcon V common core boosters used as a first stage, strapped in parallel with the second stage sustainer in the center. If Elon Musk can convert his Merlin rocket engine to burn LH2/LOX, than this rocket concept of mine is a real possibility. This rocket could put at least 40,000 pounds into LEO.<br /><br />

 

[wvbraun]

Well said.<br />

 

[john_316]

since were on the subject:<br /><br />what is the maximum payload to leo with a 4 segment srb?<br /><br />what is the maximum payload to leo with a 5 segment srb?<br /><br />i ask that without an upperstage....<br /><br /><br />can the srb handle a 5 meter fairing like atlas or delta heavies?<br /><br /><br />ok heres one...<br /><br />what about a delta or altlas with a single core stage and with srbs attached to them? not titans but shuttles srbs? can that lift 25+ tons to leo and or 15+ tons to lunar orbit?<br /><br />can they handle a 20+ ton CEV or Mini-shuttle?<br /><br />can the hsl-42 launch on that confiuration?<br /><br />just some questions to jar some minds...... if anyone replies to this with actual figures id greatly appreciate it cuz im a clutz when it comes to rocket science...<br /><br />

 

[tap_sa]

<font color="yellow">"what is the maximum payload to leo with a 4 segment srb?<br /><br />what is the maximum payload to leo with a 5 segment srb?<br /><br />i ask that without an upperstage.... "</font><br /><br />plain SRB without further stages is unable to reach orbital velocity even without any payload at all. So the answer to both accounts would be zero.<br /><br />A single stage to orbit using solid propellant is next to impossible. The low specific impulse of the solids requires that approximately 98% or more of the vehicles liftoff weight has to be propellant. This contradicts with solid motor design where big heavy case is a requirement because the whole motor is basicly just a big pressure vessel with an open end. The best solid stages have about 90% of their weight as propellant, SRB only ~85%.<br /><br /><font color="yellow">"can the srb handle a 5 meter fairing like atlas or delta heavies? "</font><br /><br />With a liquid upper stage, why not. Look at the CEV Stick design, the upper stage is wider than the SRB, probably in the 5m neighbourhood.<br /><br /><font color="yellow">"what about a delta or altlas with a single core stage and with srbs attached to them?"</font><br /><br />EELV cores cannot cope with the amount of thrust that pair of SRBs would produce (you'd need minimum of two for stability). In general SRBs are good only if you put relatively heavy second stage on top of it, or, strap two or more paraller to something <i>very</i> heavy and sturdy, like ET or proposed SDHLV first stage tank. Other options don't either fly at all or rip themselves apart at some point during the flight.

 

[john_316]

So we would assume the the SRB CEV version would most likely use a 5 segmented SRB with either a 4 or 5 meter fairing and a cyrogenically stored second upper stage with a RS-68 or J-2 rocket motor?<br /><br />I mean the CEV (CM) command module and (SM) service module would have to be significantly longer than the previous Apollo era modules and be fundamentally lighter with newer materials.<br /><br />Now how big do you make the CM of the CEV in comparison to the original Apollo CM?<br /><br />Or is T/Space ideas worth it?<br /><br />Perhaps we should build more than 2-4 CEV configurations and fly them all on the SRB and EELV's...<br /><br />Not only that we would need over 12m3 cabin volume correct for a crew of 6 in suits?<br /><br />So possibly looking at a CM length of between 5 and 7 meters and a 5 meter diameter weighting in at approx 12,000 to 15,000 lbs for the CM.<br /><br />Now the SM (Service Module) would have to be lighter than the Apollo era SM as well in about a 5 meter diameter with a length of 10m and weight of 25,000 lbs max due to new materials. <br /><br />Ok....<br /><br />I know it can be done and all weight in at under 40,000 lbs which is the magic 20 ton range or less...<br />

 

[krrr]

"26,000 pounds? Hmm..."<br /><br />I meant 13 metric tons or tonnes which is 29000 pounds, and I was simply extrapolationg from the 18 tonnes mentioned in the astronautix article.<br /><br />Otherwise, no real qualms with your ideas. I'm all for a simple lightweight CEV for ISS passenger missions.<br /><br />

 

[dwightlooi]

Lets get a few facts straight:-<br /><br />(1) No matter which LV is used -- Delta IV, Atlas V, SRB, or something entirely new -- you are going to need a new launch infrastructure. The current shuttle and EELV launch towers and platforms won't work. The EELV ones have no provision for crew entry and egress. And you can't have a crew sit in a capsule and wait 6 days. The shuttle pad will not take an EELV or a Shuttle SRB on it's own.<br /><br />(2) So, when they talk about infrastructure reuse and usage continuance, they are talking about manufacturing facilities, already man rated engines and the like.<br /><br />IMHO, I think NASA will be foolish to try to clobber together a half assed CEV launch vehicle emphasising maximum use of existing configurations. The idea behind solid first stage booster is attractive from a launch readiness standpoint. This is especially true if the second stage uses storable propellants (say UDMH or MMH with N2O4). Such a rocket can be stored for year and used within minutes. It'll be a good system for rescue missions and for rapid reaction scenarios. Ideally you can build dozens of them and store them in self-erecting cannisters, you simply tow them out to the launch pit, let the crew climb in and away you go.<br /><br />However, I think it is a mistake to base a solid booster on the Shuttle SRB. It is not efficient to bolt a 4 or 5m upper stage to a slim, slender, 1.43 m SRB. If you want to use an SRB first stage, make it a shorter 4 or 5m SRB.

 

[vt_hokie]

I believe the Conestoga launch vehicle used solids to get all the way to orbit. However, I think they only launched it once, and the payload never made it to orbit.

 

[dwightlooi]

<br /><br /><i>I meant 13 metric tons or tonnes which is 29000 pounds, and I was simply extrapolationg from the 18 tonnes mentioned in the astronautix article.<br /><br />Otherwise, no real qualms with your ideas. I'm all for a simple lightweight CEV for ISS passenger missions. </i><br /><br />18 tons is not simple and light, neither is 13 tons. A Soryuz is about 6.5~7 tons. The Shenzhou is 8 tons. Now these are all 3 passenger capable vehicles with a service module and all the other stuff needed to sustain astronauts for almost a week when the vehicle is used as a stand alone orbital craft.<br /><br />I Think NASA should do a 8 ton Crew Transfer Vehicle. The role of this vehicle should be to move up to 6 astronauts to orbit and transfer them to the ISS or a larger CEV. This vehicle does not need more than 24 hours of life support. It does not need a service module. In essence the EELV's or SRB derived booster's upperstage becomes the service module. It's only role is to pack as many humans as possible and take them to orbit. If you need to stay there for more than a few hours, you transfer them to a CEV or the ISS. <br /><br />A Separate CEV with no re-entry capability should be developed for use solely as a space vehicle.

 

[cuddlyrocket]

Robert Zubrin also proposes a small CEV (see the Mars Society website for the article). I tend to agree. The purpose of the CEV is to get 3/4 astronauts to/from the ISS and to act as a command and return module for Moon and other missions. It need mass no more than Soyuz for that.<br /><br />A CEV launcher would need a new launch tower. However a SDLV could be launched from an adapted Shuttle tower, which is what I think they have in mind when talking about same.

 

[john_316]

this link is from the 1st of july so i dont know what to make of it but if its reliable then this waht we will see take shape...<br /><br />http://www.comspacewatch.com/news/viewnews.html?id=1040<br /><br />i would think this is legit but its hard to say with way things are going. <br /><br /><br /><br /><br />

 

[frodo1008]

Would all of you people who are fully expecting Ed Musk to get us into space cheaply at least wait until he has been successful with the Falcon I, before fully committing to Falcon V, which at this time is just a paper study. At least Musk himself has had the good sense to admit that just getting the Falcon I itself ready was far more of an effort than he originally thought it would be!<br /><br />I am NOT saying that he can't do what he says (and I would be personally delighted if he can!), but we HAVE heard this sort of thing before. There IS an interesting rule of thumb here. Take any large aerospace (or any other project for that matter) project, and make as good an estimate of the time and costs for such a project as you can (remember that for many such projects there is very little already known about what you are going to try to do) and then DOUBLE the estimates! Now, you might even have a workable number. If you had used your original estimates, and exceeded them by some 50% (S__T happens, you know, high pressure equipment has a very unfortunate habbit of suddenly blowing up!) then your superiors will obviously take great glee in kicking your backsides! On the other hand if you have given an estimate with a 100% overrun, they will pat you on the back! <br /><br />I know this sounds downright dishonest if not unethical, and I personally don't like it. However, in more cases that not it is what you have to do! <br /><br />One of the main problems with the shuttle cost was that NASA unfortunately had to do the complete opposite to this in order to even get ANY kind of funding to build a completely reusable STS system. NASA's original promises (while I fully believe these estimates were as valid as NASA could come up with) were just a tad off of reality! Like some 2,000%! In light of this I do have a tendency to take very low launch cost estimates for any new system by either NASA or pure privete interests with a certain proverbial grain of salt!!<br /><br></br>

 

[spacester]

frodo1008,<br /><br />IMO it would be best for all if you were just a *teensy* bit more accepting of the opinions of others.<br /><br />I'm sending a PM rather than post what I just wrote.<br /><br />Collaboration is a good thing. Cynicism is an enemy of collaboration.<br /><br />Have a nice day! <div class="Discussion_UserSignature"> </div>

 

[john_316]

well if you all want to know i have a xjr-45 saucer for sale. real cheap runs on element 115 and test driven by bob lazzar once....<br /><br />ill sell it cheap......<br /><br />good for another 150,000 ly<br /><br /><br />

 

[dwightlooi]

If the idea is to use have a extinguishable or throttlable solid hybrid, it is probably better to use Butadine (rubber) along with an oxider. Rutan uses Nitrous Oxidem but N2O4 should work too.